Photographic element and process utilizing antibronzing agents



INVENTORS La/z/wzaak gil J. D. KENDALL ET AL Filed NOV. 8, 1945 EMnJ/a/vca/vm/A//M 5MM/wam Oct. 30, 1951 PHOTOGEAPHIC ELEMENT AND PROCESS UTILIZING ANTIBRONZING AGENTS ozylmf'Jmflg 829%@ Wm M iff/fw ATTORNEYS Patented Oct. 30, 1951 PHOTOGRAPHIC ELEMENT AND PROCESS UTILIZING AN TIBRONZING AGENTS John David Kendall and Douglas James Fry, Ilford, England, assignors to Ilford Limited, Ilford, Essex, England, a British company Application November 8, 1945, Serial No. 627,518 In Great Britain November 13, 1944 16 Claims.

This invention relates to compounds which serve as improvers for photographic silver halide emulsions and particularly to compounds which, when included in the emulsion layer, or in another layer present in the photographic material, or When added to the developer, xer or other processing bath applied to the photographic material, improve the quality of the developed photographic images obtained.

In the production of photographic images in silver halide emulsions, and particularly in the case of emulsions in which the silver halide is predominantly silver chloride, the maximum image density obtainable is not always so great as may be desired. Moreover, the common practice of hot-glazing photographic prints tends to affect adversely the image colour, giving a poor quality black having a bronzed appearance, and also reduces the eiective maximum density obtainable in the image.

It has now been discovered that this bronzing effect may be reduced or eliminated and the maximum density obtainable may be increased by bringing into contact with the photographic emulsion .a member of a certain class of heterocyclic nitrogen compounds, and according to this invention, therefore, a method of improving photographic silver halide emulsions in regard to the quality of the images developed therein comprises including in the emulsion, or in another vlayer of a photographic element containing such emulsion, or in a developing, xing or other processing bath with which the photographic element is treated, a heterocyclic compound containing two nitrogen atoms in the ring and one, tWo or three sulphur atoms attached to carbon atoms which are in v:1r-positions to the nitrogen atoms (but excluding the case where a single sulphur atom is present and attached to a carbon atom which is A:i to both nitrogen atoms), the nitrogen atoms being unsubstituted. Such compounds contain at least one sulphur atom attached to a carbon atom a to a nitrogen atom on one side and an atom of an element different from nitrogen on the other side. Typical forms f compound `are those having the groupings:

IS I I -NH-NH- C- as part of the heterocyclic ring. The compounds of the type s NH-(HJ-NH- Where X is an oxygen `atom or a sulphur atom and Y is an oxygen atom, a sulphur atom or an imino group. Examples of this class are:

2 :5-dimercapto-l :3 :4-thiodiazole 2-mercapto-5--amino-1 :3 :ll-thiodiazole B. Compounds which have one of the following tautomeric forms:

s SH 'if' \NH 'Ill' \N D"\ /Ilm S /Iq o c i im where D represents the carbon atoms completing a six-membered ring and may include a fused benzene ring, and Y is oxygen, sulphur, or an imino group. Examples of this class of compound are:

1-mercapto-4-hydroxy-phthalazine l :4-dimercapto-phthalazine C. Compounds of the general formula:

S Il C ,l NH

where D and Y have the same significance as in B above. Examples of this type of compound are: Z-hydroxy-l-mercapto-pyrimidine 2 4-dimercapto pyrimidine 2:4-dimercapto quinazoline This class of compound includes compounds of the general formula:

where Y has the same significance as Igiveri" above. An example of this type of compound is trithio barbituric acid. A, i

It will be understood that all thesel compounds may exist in tautomeric forms, the

grouping tautomerising to sn =N and that any of the tautomeric forms may be employed in this invention. The common names given to the compounds sometimes refer more accurately to the alternative tautomeric'formulae. lSome 'of the free compounds are somewhat unstable and these compounds, and indeed any of the compounds, may be used in the form of their alkali metal or ammonium salts.

As alreadyrindicated these compounds may be included inthe silver v'halide photographic emulsion or in another layer of the photographic element, preferably coated adjacent to such emulsion layer, for example in a sub-coat layer or in a super-coat layer. -Theoptimum quantity of compound to be employed will always be small, but willdepend on the particular substance selected. In general it is found that for incorporation in lan emulsion, sub-coat or super-coat, a proportion of 1V part of the compound in 1000 to 100,000 of the emulsion, super-coat or subcoat solution is'gen'erally suitable, while for incorporation ina developer, liixer or 'other processing bath, eig-af glazing solution; the optimum quantity may be, for example, between vlpart-in 3000 to 1 part in 300,000 parts of the processing solution. Frequently even lower concentrations than those given `above have some effect and, though it may -be 'unecono'mic in being a waste of material, even higher concentrations may be employed.

More than one compound of the type defined may be used if desired, and the compound or compounds may be included in more than one position, el g. in 'super-'coat and'developingf'so'lution,`or in both developing`V and fixing Solutions.

In general'the "compounds will be applied "to the"photographic emulsion before reaching 'the iinal stage of drying the developed image, but they may be applied with advantage to-already dried prints where it is desired to subject the latter to hot-glazing.

The following examples 'illustrate theinvntion:

Example 1 To a silver chloride photographic emulsion of the type known asa vigorous gaslight emulsion (A) and to a silver'bromide emulsion of the type used for vigorous bromide printing paper ('B) was' added 21 cc. ofV a 0.5%solution-in'ethyl alcohol of 2:5-dimercapto-1:3":4-thiodiaole per litre of emulsion. The emulsions were coated on paper. Comparative tests (controls) were made with the sameemulsionsnot containing 'the said compound. Test vstrips 'of the 'papers' 1thus obtained were exposed, developed, fixed, washed and hot-glazed shortly after coating, and similar test strips were exposed, developed, xed, washed and hot-glazed after the paper had been kept for some hours in a warm :'moist atmosphere (i. e. ""'incubate'd"). vThe test "strips were examined visually and sensitometrically and gave the following results:

Maximum Maximum Degree of dseallsllt'egf density of Y'Eriiiflsion,"(A'o'r B) bronzing after tesged incuhot-glazing h hated s ol'mrsamples after coatmg ontrol'.-.` f..l; considerable... 1.72 1.69 Tests A containing the very much re- 2.10 2.00 ,abovecompound duced. ControlB considerable..- 1.64 1.90 Tests B containing the much'reduced. 1.97 2.03

above compound.

Example 2 To `a gelatin# super-coat solution was added-22 cc. of a '0.5% solutiony in ethyl alcoholof2:5di mercapto-l :3 4-thiodiazole per Yli-treof vthe'supercoat solution. vThisl solution was coated-fom-the surface of layers of thefemulsions referredfto-in Example l carriedv on paper supports.ontro1 tests were made withsuper-coats tof-'similar composition but not containing the saidcOmpOuIId.

Test strips were prepared as inExample 1 Jand the following resultswere obtained:

` Maximum Maximum i "Degecbf zinsltesf.. idensityof Emulsion (A or B) bronzing after .testpd "incu- "hot-'glazing h bated fs only.' 'samples 'after coating Control A considerable... 11:72 16.69 estsA .much'r'edu'ced. `2.06 2.02 Control B.- considerable... 1. 64 1.90 Tests B much'reduced 1."98 2502 Eic'mple lThe procedure of Example. 2 iwasfollowed Awith the 'following' compounds inthe @quantities indicated:

(e) v2:lidirnercaptocquinazcline.s s. (j) '.Trithio'barloituric-aoid ;1 1s 1i :22 In au cases the 'controrsamplesshowed considerable bronzing on` hot-glazing,"wherasin' the 'test samples thedegree nfbron'Zing 'wasmih' 'reduced or entirely eliminated. "The 'follwingtablesets out themaximumensity of the` images obtained after hot-glazing shortly" after" ''atirg Z It will be seenthat in au cases a substantial increase in the maximum density' was obtained,

aravaca? A 1:500 solution of 2:5-dimercapto-1z3:4-thiodiazole in N/25 sodium carbonate solution was prepared. This Was added to a 20% acid hypo xing bath at the rate-of 75 cc. per litre, The :fixing bath thus prepared was employed for fixing developed images in a normal gaslight printing paper (A) of which the silver halide of the emulsion was primarily silver chloride, and in a normal bromide printing paper (B) of which the silver halide of the emulsion was primarily silver bromide. Control tests were carried out at the same time with a similar xing bath not containing the compound. The results obtained were as follows: f

The accompanying drawing further illustrates the present invention. Figures 1, 2 and 3 are sectional views showing a suitable photographic support layer I to which is applied the anti-bronzing agent of the present invention. In Figure 1, the support I0, which may be the conventional photographic paper, contains the anti-bronzing agent in the emulsion layer II. In Figure 2 the support I has applied thereto an emulsion layer I2 and a super coat I3 containing the anti-bronzng agent. In Figure 3 the support I0 and the emulsion layer I2 are separated by a sub coat I4 containing the anti-bronzing agent.

What We claim is:

1. A photographic element including a photographic silver halide emulsion layerand in contact therewith and uniformly distributed thereover a heterocyclic compound selected from the class of those represented by the following general formulae:

and

Where X is selected from the class consisting of oxygen and sulphur atoms, Y is selected from the class consisting of oxygen and sulphur atoms and imino groups, and D is selected from the class consisting of substituted and unsubstituted carbon atoms completing a six-membered ring.

2. A photographic element as defined in claim 1 in which the heterocyclic compound is 2:5-dimercapto-l 3 4-thiodiazole.

3. A photographic element as dened in claim 1 in which the heterocyclic compound is 2-mercapto-5-amino-1:3:4-thiodiazole.

4. A photographic element as defined in claim 1 in which the heterocyclic compound is l-mercapto-4hydroxyphthalazine.

5. A photographic element as defined in claim 1 in which the heterocyclic compound is 1:4-dimercapto-phthalazine.

6. A photographic element including a photographic silver halide emulsion layer which contains uniformly dispersed therein a heterocyclic compound Selected from the class of those represented by the following general formulae:

whereX Yis selected from the class consisting of oxygen and sulphur atoms, Y is selected from the class consisting of oxygen and sulphur atoms and imino groups, and D is selected from the class conisting of substituted and unsubstituted carbon atoms completing a six-membered ring.

7. A photographic element as defined in claim 6 in which the heterocyclic compound is 2:5-dimercapto-l :3 4-thiodiazole.

8. A photographic element as defined in claim 6 in which the heterocyclic compound is 2-mercapto-5-amino-l :3 4-thodiazole.

9. A photographic element as dened in claim 6 in which the heterocyclic compound is l-mercapto-4-hydroxy-phthalazine.

10. A photographic element as dened in claim 6 in which the heterocyclic compound is 1:4-dimercapto-phthalazine.

11. A photographic element including a photographic silver halide emulsion layer and, adjacent thereto, a water-permeable colloid layer containing uniformly dispersed therein a heterocyclic compound selected from the class of those represented by the following general formulae:

EIlE

where X is selected from the class consisting of oxygen and sulphur atoms, Y is selected from the class consisting of oxygen and sulphur atoms and imino groups, and D is selected from the class consisting of substituted and unsubstituted carbon atoms completing a six-membered ring.

12. A photographic element as defined in claim 11 in which the heterocyclic compound is 2:5-dik mercapto-l :3 4-thiodiazole.

'EEFEENQES n @FEED sdf NH "The following `references areof Y record in the 1X-----'JJ=Y 10 levofithis patent:

all?

and

NH 22519;09'0 igis'ra et a1. QMyiiQQ TIf-H-.-v--'f-i "C 371,315 Russell June 5, 1945 EnI :24,233.67 ,Evy i :zgguiy s, 1947 where X is selqcted lfrom @he class cgpssting 20 FOR'EIGN PATENTS i of loxygen and sulpljryr atomsfYfis seiectedff'ron vNumber Country Dalle the class consisting ofoxygen and suiiphuratoms 524,556 C11-eat Britain fi- -Aug. 13%,() 

1. A PHOTOGRAPHIC ELEMENT INCLUDING A PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER AND IN CONTACT THEREWITH AND UNIFORMLY DISTRIBUTED THEREOVER A HETEROCYCLIC COMPOUND SELECTED FROM THE CLASS OF THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULAE: 